In U.S. Pat. Nos. 4,229,456 and 4,133,885, naphthyridine derivatives of structure: ##STR3## in which X can be oxygen and two of the adjacent radicals R.sub.1 to R.sub.5 can form a benzene ring, have been described.
These products are useful as inhibitors of acidic gastric secretions.
Patent application DE 3,302,126 describes hypotensives of general formula: ##STR4## in which the radicals X, Y and Z can be O or a radical NR.sub.4 or CR.sub.5 .dbd.CR.sub.5, in which the groups R.sub.5 can form a benzene ring.